Earlier known air distributor have numerous disadvantages with respect to the mixing of this air with the air of the space, the slowing of the air, the necessary connection pressure and the uniform ventilation of the space. A primary disadvantage is that a plate disposed ahead of the mouth of the connecting pipe distributes the impinging air stream so that the stream also includes radial velocity components. The air stream flowing radially from the opening becomes, as a result of the rapidly increasing flow cross section, significantly slower even at a relatively limited distance, i.e. loses its injection velocity before the injected air has intensively mixed with the air of the space. Because of the failure of an intensive mix, the temperature difference between the air of the space and the injected air remains in large measure which results in drafts in personnel-containing spaces especially when cold air is injected.
There are air distributor structures known in which a corresponding mixing and deceleration of the injected air can be attained. These constructions, however, operate with high connection pressure and involve significant ventilation power; in spite of the high connection pressure, the ventilation air quantity displaced is low.
With distributor construction having a baffle and a vane grid, it is not possible to so reduce the volumetric flow of the injected air so that the injected air stream is uniformly distributed for mixture with the air already in the space. On the contrary, with this construction there is an increasing danger of air drafts as a result of the reduction of the flow. A further disadvantage of the known devices is that adjustment of the injected air quantity to a desired value in the connection pipe or in the connecting air duct for throttling the connection pressure, requires an especially costly throttle element. It is also possible to adjust the vane grid for throttling of the air stream; however this adjustment affects the uniform velocity distribution of the outflowing air stream and the vane grid, which can be visible, may have an unsatisfactory esthetic appearance because of its asymmetric setting.
In the construction of devices with air distributors it is important to ensure that the injected air, especially when it is colder than the air of the space, mixes as completely as possible with the air of the space before it enters the portions of the space occupied by people. In addition, the flow velocity must be reduced to a value which does not permit the detection of drafts. The selected flow rate must be established and controlled with the air distributor itself so that even with low pressure differentials a relatively large volumetric flow is provided; simultaneously it must also be possible to establish the flow rate at a low value with large pressure differentials so that drafts and undesirable noise or disturbing acoustic phenomena do not occur.
These contradictory requirements result in compromises with conventional air distributors so that each aspect can be improved only to detriment of the others.
In order to decelerate the air at a reduced distance, a baffle of one or more elements is provided ahead of the opening of the connecting pipe to divert the air to radially outward streams.
One can use as a baffle, circular planar plates, lying mainly perpendicular to the axis of the connecting pipe, or bodies of rotation.
The rear plate surrounding the connecting tube is thus so used that the ventilation air is diverted into radially outward streams between the rear and front baffles. The open space between the front and rear baffles is preferably optically shielded from an esthetic viewpoint. For this purpose, one or more circular plates can be arranged between the rear and front baffles or flat plates are erected in radial planes or cylindrical rods can be provided between the rear and front baffles as optical grids which influence the radially outward flow of the air as little as possible.
With this air insufflator construction, the radially outward streams of air are associated with a very low flow resistance. To adjust the volumetric flow of the injected air, adjustable throttle structures are generally built into the connecting pipe which operate to set the flow cross section. Sometimes these throttle structures are also built into the flow cross section between the rear and front baffles. A known device has throttle plates between the rear and front baffles so that they are open condition in the radial direction but, upon throttling are closed pairwise in opposite directions of rotation. A further variant of the latter for a radial flow air distributor is built into the building structure subdivided into rooms, for example, in a roof, whereby the elements of the body of rotation forming the front baffle are parallel to the building structure and are fastened in the vicinity of the plane at which the unit is mounted.
An air distributor having a radially widening vortex air stream is described, for example, in Hungarian Pat. No. 179,824. Vortex formation is here effected by feeding the air in a tangential direction within the injector device, the radial outflow of the air is obtained with a foreplate applied to the outlet opening but which does not overlie the outlet opening but rather extends parallel thereto. It is a characteristic of the construction that the reduced pressure found in the core of the vortex draws air from the space through an opening provided for this purpose in the foreplate and premixes it.
A similar solution is described in German Pat. No. 2,421,120 which relates to a rectangular air injector construction in which the air is fed laterally through a pipe connected to a large box and at its inlet into the box is diverted by a vertical guide plate ahead of the mouth opening onto a sealing distribution grid at the bottom of the box to achieve a uniform outflow of air. A vortex movement is generated in the box with an effectiveness which is sharply influenced by the rectangular cross section of the box and the rectangular cross section of the grid.
Both devices have the disadvantage that the vortex formation can be realized in the radially expanding air stream only with unusually high pressure losses and thus with considerable loss in fan work.
A known transition between axial and radial vortex injector constructions is the semiaxial proposal of Soviet Pat. No. 231,085. The vortex is generated in a special worm element into which the air is radially introduced. The pressure loss in this solution is high. The outflow of air and its distribution is effected by a conically shaped surface disposed ahead of the worm element.
The known axial vortex injector constructions have the additional disadvantage that the vortex movement of the air has a proportionally small outer surface of the air in contact with the air in the space and which serves to bring about mixing.
The known radial vortex injector constructions have the common characteristics that the expanding air stream is close to a boundary surface of the building, for example close to the ceiling so that mixing with the room air can take place only at one side of the stream.
It is also disadvantageous with this construction that control of the quantity of the inblown air requires the intervention of special expensive throttle structures.